Process of manufacturing carbons for electrical purposes.



MATENT Farce,

UNITED EDUARD POHL, OF KALK, GERMANY, ASSTGNOR, BY DIRECT ANT) MESNEASSIGNMENTS, TO ADOLPH SOHENK, OF BERGEDORF, GERMANY.

PROCESS OF MANUFACTURING CARBONS FOR ELECTRICAL PURPOSES.

SPECIFICATION forming part of Letters Patent N 0. 662,090, datedNovember 20, 1900. Application filed August 29,1899. Serial No. 728,872-(No specimens.)

T (LZZ whom it may concern: long time for forming, and, moreover, is obBe it known that I, EDUARD POHL, a subtainable in comparatively smallpieces only, ject of the King of Prussia, and aresident of attempts havebeen made to imitate its form- Kalk, near Cologne-on the-Rhine, Prussia,ing process, so as to form it in a short time;-

German Empire, have invented certain new One way is to make a carbonbody, ixnpreg g5 and useful Improvementsin Processes of Mannate the samewith hydrocarbons, embedding ufacturing Oarbons'for Electrical andElecsuch impregnated body in coal-dust, and sub trochemical Purposes;and I do hereby dejecting it to the action of heat with exclusion clarethat the following is a full, clear, and of the outer air. Another wayis to heat the exact description of the invention, which will carbonbody in an atmosphere containing 60 enable others skilled in the art towhich it aphydrocarbons. The result of either of these pertains to makeand use the same. processes has proved to be unsatisfactory, as

The present invention relates to the manuis clearly evidenced by thefact that at present facture of carbon bodies for electrical andattempts are made to improve the strength 5 electrochemical purposes,such as pencils for and density by an admixture of metallic com- 65electric lamps, contacts for generators, mopounds to the carbon. tors,interrupters, and the like, microphonic I have discovered that in orderto obtain a contacts, electrodes for electrolytical cells, perfecteffect as to the filling up of the pores 850.; and its object is toimprove that step in of the body and its conversion in the desired 2said manufacture which is commonly under.- modification of carbon thecarbon-yielding 7o stood by the term graphitizing. gas must not begenerated within the body It is Well known that carbon bodies in 01'-itself nor caused to act on a naked body, but der to be fit for use inelectrical and electro that the body requires to be embedded in achemical appliances must combine high denmass of reduced coal, which isimpregnated sity with great strength, and to obtain this with anatmosphere of said gas. In other 75 the bodies are subjected to whatcalled terms, the body has to be inclosed in an ingraphitizing, whichterm "means treating timate mixture of carbon particles and carthecarbon bodies by the action of heat and hon-yielding gas. When underthese condifilling up their pores by the deposition theretions asufficientlyhigh degree. ct heat is ap- 3 in O carbon. plied from theoutside, a very copious transa It has been found a long time ago thatthe fer or immigration of carbon molecules is carbon deposit forming onthe inside of the caused to take place from the inclosing mixretorts inwhich coal is subjected to the procture of solid carbon particles andcarboness of destructive distillation by virtue of its yielding gas intothe inclosed body, the molespecific molecular condition answers verycules of the latter uniting with the immigrat- 8; well the requirementsas to density and ing molecules and the nature of the body hestrength.This peculiar condition of the soing thoroughly modified-that is to say,the called gas-retort carbon is due to the fact body has imparted to itsuch adegree of denthat the incandescent deposit once formed is sity,strength, and hardness as are in no wise 4o constantly in contact withand penetrated obtainable by applying either of the known 9 by part ofthe hot gases generated within the processes. Carbon bodies treatedaccording retort, which partof gases by its intimate conto this improvedmethod will answer with a tact with the incandescent deposit is causedclear metallic sound when struck by means to dissociate, the carbonmolecules thus set of a hard object, their density amounts to a s freebeing deposited in the pores and upon specific gravity of 1.7, theirhardness is such 5 the surface of the deposit and welded toas towithstand the action of the best qualigether with the same, so to say.The result ties of emery, and their color shows to be by is a very denseand strong carbon, having far brighter than that of the best carbons insomewhat of the nature of the graphitic modithe market. There is,however, a serious defieation. As gas-retort carbon requires a feet inthat the surface of the inclosed body roo frequently becomes incrustedwith irregular agglomerations of carbon, which, owing to their extrememechanical resistance, it is very difiicnlt to remove, so that theproduct, though admirably well adapted in all other respects, is unfitfor use in such cases where a smooth or even surface is required.Obviously those agglomerations are due to circumstances, such asimperfect contact, which allow depositions of carbon molecules to takeplace between the inclosing mass and the inclosed body. My attempts toprevent those agglomerations from forming have resulted in the discoveryof the very striking fact that by the interposition between the body andthe inclosing mass of a thin screen composed of an organic substanceadapted to be readily transformed into coke-like carbon when heatisappiied the inclosed body is improved, as stated,withulli) anyagglomeration or incrustation being ailowe to form on its surface. Suchscreening substances are textile fabrics, sawdust, peat, starch, and thelike applied to the body as a thin layer. The best results have beenobtained by closely wrapping the body in a thin sheet of paper. In anycase the effect is striking. The inclosed carbon body is closelyencompassed in a thin envelop of a coke-like nature, which adheres in nopoint to the inclosed body, but can easily be removed from the same,leaving it with a perfectly smooth or even surface, so that the body canbe made use of without further treatment.

The impregnation of the inclosing carbon mass with carbon-yielding gascan be effected by forcing a current of such gas into the same or byimpregnating the inclosing carbon mass with such substances as give offsuch gases when heat is applied. I prefer the first-cited mode, and,moreover, I prefer to heat the current of gas prior to forcing it intothe inclosing carbon mass.

From what has been said it is easily to be understood that the presentinvention consists in its mo t perfect form in the combination, with amixture of solid carbon particles and a carbon-yielding gas forinclosing the carbon body to be treated, of a readily-forming inadhesivescreen of coke-like nature, but that in cases Where evenness of surfaceis of no importance said screen may be omitted.

I wish it to be understood that in the claims annexed the term carbon isused as comprising any appropriate description of fossil or artificialcarbon in its raw or in a prepared state, that the term paper is toinclude any carbonaceous substance capable of being readily reduced to acoke-like nature by the application of heat, and that the termcarbon-yielding gas is intended to express any non-oxidizing gas capableof giving off carbon when in contact with incandescent carbon.

In carrying out my invention I prefer to proceed as follows: A carbonbody, sl sped as desiredfor instance, a or a plateis produced in theusual waythat is'to say, by uxlXi'zifr powdered coke, charcoal,gas-retort carbon, or any other description of coal or carbon with anappropriate cementing agent such as tar, oil, and the like-and molding,all as is well known to those skilled in the art. After drying andburning, the body is closely wrapped in a sheet of paper and the wrappedbody placed centrally into a receptacle of iron or other fireproofmaterial which can be air-tightly closed and is provided with agas-inlet. The interval between the body and the walls of the receptacleis filled with reduced charcoal, coke, peat, or with lamp black and thelike, when the receptacle is closed and heated up to white heat asrapidly as possible and the current of hot gas admitted. The latter mayconsist of carbonic oxid, hydrocarbons, cyanogen or cyanogen compounds,and the like. I prefer to use a hot current of hydrocarbon gas. Afterhaving been exposed for a suflicient-long period to the action of heatthe receptacle and its contents are allowed to cool, when the receptacleis opened, the body taken out from the inclosing mass, and the coke-likeenvelop removed. 4

Having fully described myinvention, what I desire to claim and secure byLetters Patent is l. The process of manufacturing carbon bodies forelectrical and electrochemical purposes which consists in forming a bodyof carbon, and inclosing the same in an intimate mixture of carbonparticles and carbon-yielding gas under the action of heat, said gasbeing generated outside of the carbon body, substantially as described.

2. The process of manufacturing carbon bodies for electrical andelectrochemical purposes which consists in forming a body of carbon,covering the same with a thin layer of a readily-cokable substance,embedding the covered body in a mass of reduced carbon, heating with theexclusion of the outer air, and creating a carbon-yielding atmospherewithin the said inclosing mass, substantially as described.

3. The process of manufacturing carbon bodies for electrical andelectrochemical purposes Which consists in forming a body of carbon,wrapping the same in paper, embedding the wrapped body in a mass ofreduced carbon, heating with the exclusion of the outer air, andcreating a carbon-yielding atmosphere within the said inclosing mass,substantially as described.

4. The process of manufacturing carbon bodies for electrical andelectrochemical purposes which consists in forming a body of carbon,wrapping the same in paper, embedding the wrapped body in a mass ofreduced carbon, heating with the exclusion of the outer air, and forcinga current of carbonyielding gas into said inclosing mass of carbon,substantially as described.

5. The process of manufacturing carbon bodies for electrical andelectrochemical purposes which consists in forming a body of IIO carbon,wrapping the same with paper, emmy hand in presence of two subscribingwit bedding the wrapped body in a mass of renesses. duced carbon,heating with the exclusion of the outer air, and forcing a hot currentof 5 carbon-yielding gas into said inclosing mass Witnesses:

of carbon, substantially as described. FRIEDRICH MAYER, In testimonywhereof I have hereunto set GOSOMUR SOHOLZ.

EDUARD POHLJ

